CABO SAN LUCAS , Mexico -LRB- CNN -RRB- -- A `` dangerous '' Hurricane Jimena bore down Tuesday on the Mexican peninsula of Baja California , with the resort town of Cabo San Lucas lying in its path . Meanwhile , a new tropical storm was forming in the Atlantic Ocean .

A NOAA satellite image shows Hurricane Jimena off the coast of Baja California , Mexico , on Tuesday morning .

Jimena 's maximum wind speed dropped from 145 mph to 135 mph , but it still remained a Category 4 storm , according to the U.S. National Weather Service 's 11 a.m. PT -LRB- 2 p.m. ET -RRB- update .

`` Some fluctuations in strength are likely today and gradual weakening is forecast on Wednesday , '' the weather service said . `` However , Jimena is expected to remain a major hurricane until landfall . ''

Also on Tuesday , Tropical Storm Erika formed in the Atlantic , 390 miles east of the Leeward Islands , the National Hurricane Center said .

Jimena 's storm center is forecast to come ashore on Thursday morning , but the weather service warned that `` because it will be moving parallel to the coastline , any slight change in direction could have a huge impact in the location and timing of landfall . ''

Mexico 's government extended a hurricane warning for most of the southern half of Baja California -- from Punta Abreojos on the peninsula 's west coast to Mulege on its east coast , according to the National Weather Service .

A hurricane warning means hurricane conditions are expected within the warning area in the next 24 hours and people should quickly prepare `` to protect life and property . ''

`` A dangerous storm surge along with battering waves will produce significant coastal flooding along the Baja California Peninsula , '' NWS said in its 11 a.m. PT report

On its current track , Jimena 's center will approach the peninsula 's southern portion later on Tuesday and central Baja California peninsula by Thursday , the weather service said at 11 a.m. PT .

In addition to damaging winds , the storm could bring as much as 15 inches of rain , forecasters said .

Jimena -- the 10th named storm of the Pacific season -- was centered about 110 miles -LRB- 175 km -RRB- south-southwest of Cabo San Lucas , according to the weather service . It was traveling north-northwest near 12 mph -LRB- 19 kph -RRB- .

People in his town of Los Cabos , at the very tip of the peninsula , were preparing for the storm and were getting a precursor as winds and rains began to pick up , said resident Cuauhtemoc Morgan on Monday .

Morgan , who sent videos to to CNN 's iReport , said residents had protected every home in his neighborhood , fortifying windows with masking tape . Lines at supermarkets were long with worried residents preparing for the storms , Morgan said .

Authorities were setting up shelters in schools and trying to devise a plan to protect the homeless , he added .

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NEW : Tropical Storm Erika forms in eastern Atlantic , National Hurricane Center says

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Jimena 's maximum winds fell to 135 mph , but storm is still a Category 4

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The storm 's center is forecast to come ashore on Thursday morning

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Hurricane warning covers most of the southern half of the Baja Peninsula